Venuu I18n Webpack integration

I18nRuntimePlugin.js

var ConstDependency = require('webpack/lib/dependencies/ConstDependency');
var NullFactory = require('webpack/lib/NullFactory');
var _ = require('lodash');

function I18nRuntimePlugin(options) {
  options = options || {};
  this.functionNames = options.functionNames || ['I18n.t', 'I18n.translate'];
  this.translationsPlaceholder = options.translationsPlaceholder || 'I18N_RUNTIME_TRANSLATIONS';
  this.fullTranslations = options.fullTranslations || {};
}
module.exports = I18nRuntimePlugin;

/**
 * Return a single translation from the fullTranslations object using the
 * normalized keypath string ("a.string.to.translate")
 */
function resolveTranslation(keypath, locale, fullTranslations) {
  return keypath.split('.').reduce(function(previous, current) {
    if (previous) {
      return previous[current];
    }
  }, fullTranslations[locale]);
}

/**
 * Add a translation to the given object, looking it up from the
 * fullTranslations object using the given keypath
 */
function addTranslation(key, usedTranslationsForAllLocales, fullTranslations) {
  Object.keys(usedTranslationsForAllLocales).forEach(function (locale) {
    var usedTranslations = usedTranslationsForAllLocales[locale];

    // Find the last possible translation object which can be modified in-place
    // to set the new translations into.
    var objToMergeTo = key.split('.').slice(0, -1).reduce(function(previous, current) {
      previous[current] = previous[current] || {};
      return previous[current];
    }, usedTranslations);

    // Find the translation to merge into the existing translations
    var objToMergeFrom = {};
    objToMergeFrom[key.split('.').slice(-1)[0]] = resolveTranslation(key, locale, fullTranslations);

    _.merge(objToMergeTo, objToMergeFrom);
  });
}

I18nRuntimePlugin.prototype.apply = function(compiler) {

  var replacementDependency;
  var keys = [];
  var fullTranslations = this.fullTranslations;
  var usedTranslations = {};

  // Initialize all locales to empty objects
  Object.keys(fullTranslations).forEach(function (locale) { usedTranslations[locale] = {}; });

  compiler.plugin('compilation', function(compilation) {
    compilation.dependencyFactories.set(ConstDependency, new NullFactory());
    compilation.dependencyTemplates.set(ConstDependency, new ConstDependency.Template());
  });

  /*
   * Obtain a reference to the placeholder location.
   * We will decide the content later on.
   */
  compiler.parser.plugin('expression ' + this.translationsPlaceholder, function(expr) {
    replacementDependency = new ConstDependency(null, expr.range);
    replacementDependency.loc = expr.loc;
    this.state.current.addDependency(replacementDependency);
    return true;
  });

  /*
   * Collects the first argument of each call to `I18n.t` into the `keys` array.
   */
  var collectKey = function(functionExpression) {
    if (functionExpression.arguments.length < 1) return;
    var key = this.evaluateExpression(functionExpression.arguments[0]);

    if (!key.isString()) return;
    key = key.string;

    if (keys.indexOf(key) >= 0) return;
    keys.push(key);

    // Add the translation to the usedTranslations object
    addTranslation(key, usedTranslations, fullTranslations);

    // We don't know when the last call will occur, so we change the
    // replacement on every call.
    replacementDependency.expression = JSON.stringify(usedTranslations);

    return;
  };

  this.functionNames.forEach(function(functionName) {
    compiler.parser.plugin('call ' + functionName, collectKey);
  });
};